Exhaust emissions control device

ABSTRACT

Apparatus for directing air or oxygen into a stream of exhaust gases to minimize pollutants therein. In one embodiment, the apparatus is adapted to be placed in an exhaust gas flow downstream of the exhaust manifold of an engine and includes a body having a plurality of stacked plates provided with aligned openings therethrough for defining one or more fluid passages for the flow of exhaust gases therethrough. The plates form internal ducts across which an air distribution plate is disposed, the distribution plate having spaced teeth forming openings which place the ducts in fluid communication with the exhaust gas passage through the apparatus. Air directed into the ducts passes into the passages for mixture with the exhaust gases to oxidize the same and lower the pollution effects thereof. In other embodiment, the apparatus is adapted to be placed near the outlet of an exhaust valve of an engine and includes a stack of plates having air outlet openings near the outer periphery thereof.

United States Patent [1 1 Addoms et a1.

1451 Sept. 23, 1975 I 1 EXHAUST EMISSIONS CONTROL DEVICE Calif,

[731 Assignee: Aerojet-General Corporation, E1

Monte Calif.

[22] Filed: July 2. I973 [21] App1.No.;375,975

[52] US. Cl. 1. 60/307; 60/395; 60/319; 137/604; 239/555 [51] Int. Cl. .1 FOIN 3/10 [58] Field of Search 60/395, 264, 265, 304, 60/305. 307. 308, 319; 239/555; 137/604; 259/4 [56] References Cited UNITED STATES PATENTS 2,484,123 10/1949 Scherl .1 239/555 2.677.231 5/1954 Cornelius 60/303 3064.680 11/1962 Winslow 1 l A v 1 .4 137/604 3.301526 1/1967 Chamberlain. 60/3966 3.520.131 7/1970 Briggs 4 1 v 1 1 H 60/308 3,585,800 6/1971 Kuntz 60/265 United Kingdomnumh. 339/555 Germany .7 339/555 Primary E.tuminerDouglas Hart Attorney Agent, or Firm.lohn L McGannon; .11 Georg Seka; John 5, Bell [57] ABSTRACT Apparatus for directing air or oxygen into a stream of exhaust gases to minimize pollutants therein. In one embodiment. the apparatus is adapted to be placed in an exhaust gas flow downstream of the exhaust mani fold of an engine and includes a body having a plurality of stacked plates provided with aligned openings therethrough for defining one or more fluid passages for the flow of exhaust gases therethrough. The plates form internal ducts across which an air distribution plate is disposed, the distribution plate having spaced teeth forming openings which place the ducts in fluid communication with the exhaust gas passage through the apparatus Air directed into the ducts passes into the passages for mixture with the exhaust gases to oxidize the same and lower the pollution effects thereof In other embodiment, the apparatus is adapted to be placed near the outlet of an exhaust valve of an engine and includes a stack of plates having air outlet openings near the outer periphery thereof.

9 Claims, 16 Drawing Figures US Patent Sept. 23,1975 Sheet 1 0f 5 3,906,725

FIG. I6 25 22 N8 20 24 ENGINE MUFFLER US Patent Sept. 23,1975 Sheet 2 of5 3,906,725

US Patent Sept. 23,1975 Sheet 3 of5 3,906,725

FIG. 8

US Patent Sept. 23,1975

Sheet 4 of 5 US Patent Sept. 23,1975 Sheet 5 of5 3,906,725

FlG.lOb

EXHAUST EMISSIONS CONTROL DEVICE This invention relates to improvements in the reduction of pollutants in exhaust gases and more particularly, to an exhaust emissions control device which operates to admit air in a controlled manner to the exhaust gases of an engine, such as an internal combustion engine.

BACKGROUND OF THE INVENTION In view of the federal and state laws pertaining to control of exhaust gases from internal combusion engines, the need has arisen for structures associated with such an engine to receive and handle exhaust gases therefrom in a manner so as to minimize the pollutants in the gases before they enter the atmosphere. Many attempts have been made to minimize such pollutants. Generally, they have been unsatisfactory for one reason or another and improvements are needed to perform the function satisfactorily, at least to the extent of approaching and meeting the relatively strict pollution reduction requirements set forth in existing laws.

SUMMARY OF THE INVENTION The present invention is directed to an improved exhaust emissions control device which operates to emit air or oxygen to an exhaust gas stream in a controlled manner such that the air or oxygen quickly and easily enters the gas stream to aid in reducing the pollutants therein to safe levels. To this end, the device utilizes the concept of platelets or stacked plates constructed to provide a plurality of fine fluid flow paths along which air or oxygen can flow toward and into an exhaust gas stream. The flow is effectively controlled to yield optimum oxidizing effects by selectively designing the plates to form specific configurations for the flow paths. The platelet approach to this problem assures proper distribution of oxidizer through the entire crosssection of an exhaust gas stream, thereby rendering the oxidizing function more efficient than has heretofore been achievable with conventional oxidizing structures. The device of the present invention can take several forms. In one form, the device can be located downstream of the exhaust manifold of an engine, in which case it will be provided with air openings or ducts which permit air or oxygen to enter the exhaust gas stream at a plurality of locations surrounding the stream. This assures proper distribution of the air in the stream and even permits variations in the volume of the air delivered to the stream as a function of variations in the volume rate of flow thereof across the stream. The device can also be placed in the path of exhaust gases directly adjacent to and slightly downstream of an exhaust valve of an engine.

This invention will produce rapid and complete mix ing of combustion exhaust products and air. Rapid and complete mixing is required in both thermal and catalytic reactor systems to accomplish the following goals: Minimum size, minimum space requirements, minimum thermal inertia. minimum heat loss, maximum oxidation of exhaust products. and minimum downstream temperature variations. The present invention achieves all of these goals.

The present invention is superior to prior structures designed for emissions control because it operates to mix air or oxygen with exhaust gases on a very fine scale by internally manifolding and injecting the air over the entire exhaust gas flow field. In addition, the

compact nature of the platelet construction of the present invention permits it to be located in the most strategic region without significant impact on other normal engine functions.

The primary object of this invention is to provide an improved device for use in directing air or oxygen in a controlled manner into a stream of exhaust gases so that the gases will be efficiently oxidized substantially throughout its entire cross-section to reduce the pollutants therein without substantial interference with the flow of the gases away from the source thereof.

Another object of this invention is to provide a device of the type described wherein the device includes a plurality of stacked plates provided with ductdefining openings therein of relatively small size so that air or oxygen passing through the openings can be distributed in a stream of exhaust gases in a controlled manner to assure efficient oxidation of such gases notwithstanding the fact that the stream may have a relatively large cross-section.

A further object of this invention is to provide a device of the aforesaid character which can be placed at any one of a number of operative locations with respect to the cylinders of an engine, such as downstream of the exhaust manifold thereof or directly adjacent to and downstream of an exhaust valve.

Other objects of this invention will become apparent as the following specification progresses, reference being had to the accompanying drawings for an illustra tion of several embodiments of the invention.

In the drawings:

FIG. 1 is a schematic view of an engine provided with the exhaust emissions control device of this invention coupled to the downstream side thereof;

FIG. 2 is an enlarged side clevational view of one form of the device, parts being removed to illustrate details of construction;

FIG. 2a is a view similar to FIG. 2 but showing one of the plates of the device;

FIG. 3 is a view similar to FIG. 2, but showing the opposite side of the device.

FIG. 4 is an enlarged, fragmentary cross-sectional view taken along line 44 of FIG. 2;

FIG. 5 is a view similar to FIGS. 2 and 2:1. but showing another plate of the device;

FIG. 5a is an enlarged, fragmentary, side elevational view of the plate shown in FIG. 5.

FIG. 5b is an end elevational view taken along line Sb-Sb of FIG. 5a;

FIG. Se is a view similar to FIG. 2a but showing a variation thereof;

FIG. 6 is a schematic view of the device, showing the pattern of the airflow in the exhaust gas passages thereof;

FIG. 7 is a fragmentary. perspective view of a second embodiment of the device;

FIG. 8 is a vertical section through a part of an internal combustion engine showing the way in which the device of FIG. 7 is disposed near an exhaust valve of the engine;

FIG. 9 is a view similar to FIG. 7 but showing a third embodiment of the device near an exhaust valve;

FIG. I0 is a side elevational view of one of the plates of another embodiment of the device.

FIG. 10a is a side elevational view of a second. ducted plate of the device of FIG. I0; and

FIG. I]: is a side clevational view ota third. toothed plate of the device of FIG. II).

A first embodiment of the emissions control device of this invention is broadly denoted by the numeral 10, and is shown in FIGS. 2-5. Device I0 includes a body 12, comprised of a stack 14 of plates having the same outer configuration and provided with exhaust passages l5, l7, and 19 therethrough. The purpose of device is to permit an air flow to be directed into passages l5, l7 and 19, and thereby into an exhaust stream flowing through the passages. A typical exhaust stream is one that issues from the exhaust manifold of an internal combustion engine 16. A typical application of device 10 is shown in FIG. 1, wherein the device is shown con' nected by an exhaust pipe 18 to engine I6 and by an exhaust pipe 20 to a muffler 22, the latter having a tailpipe 24 for directing the exhaust gases to the atmosphere. Air is admitted to device I0 under pressure or by aspiration through an inlet tube 26. If air under pres' sure is used, tube 26 is coupled to a blower or other suitable air source. coupled to engine 16.

The various plates of stack 14 are bonded together in a manner such that passages 15, I7 and 19, thereof. are all in alignment as shown in FIG. 4. The portions of certain plates on opposite sides of each such passage differs somewhat from those portions of adjacent plates for a purpose to be described.

Stack I4 has a pair of opposed end plates 28 and 30 (FIG. 4) of substantially the same configuration, except that plate 30 has a hole 32 thercthrough (FIGS. 2 and 5) in fluid communication with tube 26. The openings in plates 28 and 30 which define passages l5, l7 and I9, are stamped or etched through the plates, leaving the plate portions around the passages intact or undisturbed. Plates 28 and 30 cover an internal air chamber 34 (FIG. 2) which communicates with hole 32 to reccive air from tube 26. Chamber 34 communicates with four elongated internal ducts 36, 38, and 42, which progressively decrease in depth as they extend away from chamber 34. FIG. 4 shows the configurations of ducts 38 and 40, and indicates that the depth of such ducts at the particular location along their lengths is less than the thickness of stack 14.

A number of plates 44 are disposed between plates 28 and 30. Plates 44 differ from each other only in the way in which they operate to form respective parts of chamber 34 and ducts 38-42. For instance, as shown in FIG. 21!, plate 440 has an opening 46, forming a part of chamber 34 and finger-like openings 48, 50, 52 and 54 which form corresponding parts of ducts 38, 40, 42 and 44, respectively. The lengths of openings 48-52 are shorter than the full lengths of ducts 38-42. This is because plate 44a is in an intermediate position in stack 14 as shown in FIG. 4. Openings 46, 48, 50, 52 and 54 are formed by stamping or etching. resulting in wicketlike extensions 56, 58 and 60, which are interconnected by short webs 62 and 64, respectively. The lengths of openings 48-52 of plates 44 on opposite sides of plate 440 will be shorter and longer. respectively'. thus. the depths of ducts 38-42 will vary as mentioned above when the various plates 44 form stack 14.

An air distribution plate 66 (FIGS. 4 and S] is disposed in stack I4 between end plate 28 and the next adjacent plate 44h (FIG. 4). Plate 66 has a plurality of openings 68, 70 and 72 corresponding to and in alignment with passages l5, l7 and 19. Plate 66 also has a plurality of spaced. rectangular teeth on the opposed sides of each of openings 68, and 72. For instance. teeth 74 are provided at opposed sides of opening 68; teeth 78 are provided at opposed sides of opening 70; and teeth 82 are provided at opposed sides of opening 72. As shown in FIG. 5a. teeth 74 and 78 are staggered relative to each other and are integral with a central band 86 forming a part of plate 66. Similarly. teeth 78 and 82 are staggered relative to each other and are integral with a band substantially identical to band 86. The teeth of plate 66 are substantially identical in size and extend partially across ducts 38-42 with the spaces between the teeth defining spaced. rectangular ports 79 (FIG. 5b) in fluid communication with the ducts. In this way, air directed into the ducts can flow into passages 15, I7 and 19 to oxidize the exhaust gases flowing therethrough with such oxidation taking place in a relatively short mixing distance. such as about one inch or less. FIGS. 4 and 50 show the way in which air flows out of the ducts. through ports 79, and into the adjacent passages. Such airflow is denoted by arrows 88. The length of each port is a number of times less than the length of the corresponding duct so that the effective areas of the various ports are sufficiently small to assure uniform. homogeneous entry of air into the exhaust gases flowing through passages I5, 17 and 19.

The number of ports 79 for each of passages 15. I7 and I9 is selected to provide a uniform distribution of airflow into the passages. Typically. the length of passages 15 and 19 is about 1.50 inches. the length of passage 17 is about 1.875 inches, and the width of each of these three passages is about 0.30 inches. For these lengths. there are typically 15 ports 79 on each side of each of passages 15 and I9 and I8 ports 79 on each side of passage 17. The effective area of each port is controlled by the spacing between corresponding teeth and the thickness of plate 66.

Since ducts 3842 decrease in depth as they extend away from chamber 34, the volume rate of flow of air into passages l5, l7 and 19 is lower at duct locations remote from chamber 34 than at locations closer to such chamber. The reason for this is to maintain a nearly constant air velocity in the duct which results in the most uniform air distribution. Thus, it is advantageous to admit the most air from ducts 38-42 at their upper ends and less air from their lower ends. This is the reason for the variations in depth of the ducts since device 10 is used with chamber 34 above ducts 38-52.

It may be desirable to provide a constant depth for the ducts for reduced cost or weight purposes. In such a case, all plates 44 will be of the same configuration and will have duct-defining openings 90, 92 and 94 and 96 surrounding continuous extensions 98, I00 and 102 connected to adjacent structure by webs I04, I96 and 108 and 110. The airflow into passages 15, I7 and 19 using identical plates 44 is shown in FIG. 6 and indicated by the plurality of conical projections I12. Also. teeth 74, 78 and 82 can be non-uniform in size and/or spacing to provide other types of flow patterns. if desired.

In use. device 10 is coupled with pipes 18 and 20 (FIG. 1) so as to be disposed to receive exhaust gases from engine 16. Tube 26 is coupled to a source of air under pressure or is merely open to the atmosphere. In the latter case, air is sucked into device 10 from the atmosphere by asperation due to the exhaust gas flow through passages l5, l7 and I9.

Assuming. for instance. that air is forced into device and that engine 16 is operating. air will enter chamber 34 and pass into ducts 36. 38. 41) and 42, from whence the air will flow out of the ducts, through the spaces between the teeth of distribution plate 66 and into passages 15, 17 and 19 for mixture with the exhaust gases from the engine. Since the ducts effectively surround the passages, air or oxygen can quickly and easily enter substantially the entire cross-section of the exhaust gas stream. yet such an entry of air does not in terfere with the flow of exhaust gases. In this way. the oxidizing effect of the air reduces pollutants in the exhaust gases in a controlled manner before such gases are expelled to the atmosphere.

Device 10 can have other configurations such as a circular configuration wherein the device is formed from a stack of circular plates including a pair ofcircu lar end plates 110 (only one of which is shown in FIG. 10), a plurality of intermediate plates 112 (only one of which is shown in FIG. 10a). and an air distribution plate 114 (FIG. 10h). One ofthc end plates 110 has an air inlet opening 116 corresponding to opening 32 (FIG. 2) of end plate 30. The other end plate 110 has no such opening 16.

Both end plates 110 have circular, generally concentric exhaust gas passages I18. 120. 122 and 124 extending about a common central axis. Similarly. each plate 112 (FIG. 10a) has concentric openings I26, 128. l and 132 which are aligned with respective passages 118. I20. 122 and 124 for the passage of exhaust gases thercthrough. Also, each plate 112 has a circular outer duct I34 communicating with a recess 136 aligned and communicating with hole 116. A number of inner ducts I38, 140 and 142 are concentric to outer duct 134 and communicate therewith by radial ducts 144 and 146.

Plate 114 (FIG. 101)) has concentric openings 148, 150. I52 and 154 which are aligned with respective passages I18, I20, I22 and 124 of end plates 110 (FIG. 10) and with respective openings 126, 128, 130 and 132 of the various intermediate plates 112 (FIG. 10a). Plate 114 also has a plurality of spaced teeth on 0pposed sides of each of openings 148, 150, 152 and 154, the teeth being operable to extend partially across respective ducts of the plate 112 next adjacent to the end plate 110 without hole 116 substantially in the same manner as that shown in FIG. 5a. When the various plates I10. I12 and 114 are assembled in a stack. the teeth define air exit ports placing the ducts in fluid communication with openings 148, I50, 152 and 154. The outer peripheral teeth of each of the lastmcntioned openings are wider than the corresponding inner peripheral teeth to keep the effective areas of the ports defined thereby substantially equal in size to assure a substantially uniform, homogeneous airflow into the exhaust gases passing through the device. The size of and spacing between the teeth can be such as to provide other airflow patterns. if desired.

In use, the emissions control device constructed with plates 110, I12 and 114 operates essentially in the same way as that shown in FIGS. 1-5 in that air entering hole 116 passes into the ducts of plates 112 and out of the ducts through the spaces between the teeth of plate 114 into the exhaust gases flowing through passages I18. 120, 122 and 124 of end plates 110 and through openings 126, 128, I30 and 132 of plates 112. The gases are thus oxized in a controlled manner before they are expelled into the atmosphere.

FIGS. 7 and 9 show two additional embodiments of the invention. In FIG. 7 device has a tubular body 162 provided with a platelet assembly 164 at one end thereof. Assembly 164 is provided with a plurality of air outlet ports 166 in two circumferential rows, the airflow outwardly of openings 166. being denoted by ar rows 168.

Platelet assembly 164 is comprised of a group of stacked plates having one or more internal airflow ducts formed therein such as by etching or stamping, the plates forming a unit through which air can be controllably directed. Body 162 is in fluid communication with the internal duct or ducts coupled to a suitable source of air under pressure. such as a pipe 170 (FIG. 8) adapted to be coupled to the outlet of a blower (not shown). Body 162 is suitable for use in directing air or oxygen into the exhaust gas stream leaving an engine cylinder 172 past the adjacent exhaust valve 174. The end of body having platelet assembly 164 is disposed within a chamber 176 immediately downstream of the exhaust valve but upstream of the exhaust manifold 178 in which pipe 170 is conveniently disposed. Thus. air or oxygen can be directed into the exhaust gases as they leave the cylinder through the exhaust valve but before the gases pass into the exhaust manifold.

In FIG. 9, device 180 is comprised of a platelet assembly 182 of horseshoe-shaped or U-shapcd configuration surrounding valve stem 184 of an exhaust valve 186. A tubular body 188 is in fluid communication with internal airflow ducts (not shown) within platelet assembly 182. Such ducts are formed in substantially the same manner as the ducts of device 10 (FIG. 2). An air distribution plate 189 having spaced teeth disposed at least partially across the ducts defines air outlet ports on the outer faces of the spaced sides of assembly 182. Thus, air can exit from ports 190 as shown by arrows 192.

The benefits derived from the use of any embodiment of the device of the present invention includes a significant reduction in the carbon monoxide and unburned hydrocarbons in exhaust gases from internal combustion engines and a uniform, homogeneous flow of air from the device into the exhaust gases as they pass through the device itself. Reductions of 90% or greater in both the carbon monoxide and unburned hydrocarbons can be achieved with the device. The device can also be used with a catalytic converter and can be used with a thermal reactor equally well.

We claim:

1. An exhaust emissions control device comprising: a platelet assembly including a multiplicity of stacked. interconnected plates, the plates having first aligned cutouts defining an elongated exhaust passage extending perpendicularly to said plates through said assembly, and aligned second cutouts spaced from the first cutouts and defining an elongate airflow duct extending generally perpendicularly to said plates through said assembly. a plate member connected to one end of said stacked plates, the plate member defining another first cutout aligned with the first cutout in said stacked plates and a multiplicity of spaced-apart outlet ports distributed along a peripheral margin of the first cutout in the plate member. the outlet ports being further positioned and dimensioned to overlie the second cutout defined by the plate in contact with the plate member to thereby place the airflow duct in fluid communication with the exhaust passage through the assembly.

each port having a linear extent along the peripheral margin of the first cutout substantially less than the total length of the peripheral margin, a pair of end plates placed against and connected to the plate member and to another end of the stacked plates, the end plates including first cutouts aligned with the first cut outs in the assembly and the plate member to define a continuous exhaust gas passage through the assembly, the end plates further closing the airflow duct to prevent fluid communication between the duct and the exterior and to direct fluid flow in the duct through the ports and into the exhaust gas passage, and means defining a fluid flow conduit for connecting the airflow duct with a source of an oxidizing fluid, whereby the oxidizing fluid entering the duct will pass through the ports into the exhaust gas passage and will oxidize the gases in the passage to reduce the pollutants therein.

2. An exhaust emission control device according to claim 1 wherein the ports are evenly distributed over the peripheral margin of the exhaust gas passage to effect a substantially homogeneous mixture of exhaust gas and oxidizing fluid in the exhaust gas passage.

3. An exhaust emissions control device according to claim 1 including an exhaust gas flow conduit attached to the device, and wherein the device is mounted to the exhaust gas flow conduit so that the ports are positioncd at the upstream end of the exhaust gas flow through the device.

4. An exhaust emissions control device according to claim 1 wherein each plate of the assembly, the plate member and the end plates define a plurality of spaced apart first cutouts to define a plurality of parallel exhaust gas passages through the device, the plates and the plate member further defining a plurality of second cutouts to define a duct on each side of each first cut out, and wherein the ports are defined by a multiplicity of spaced-apart teeth of said plate member extending partially across respective ducts so that the ports are defined by spaces between the teeth.

5. An exhaust emissions control device according to claim 4 wherein the spacing between the teeth is nonuniform.

6. An exhaust emissions control device according to claim 4 wherein the width of at least certain of said teeth is different from that of the other teeth to maintain the CffCCll\ e areas of corresponding ports substantially equal to each other.

7. An exhaust emissions control device according to claim 1 wherein the depth of the duct in a direction parallel to the exhaust gas passage is substantially imiform.

8. An exhaust emissions control device according to claim I wherein the depth of the duct in a direction parallel to the exhaust gas passage varies along said pe ripheral margin.

9. An exhaust emissions control device installed in an exhaust gas pipe line having exhaust gas flowing there through, the device comprising: a multiplicity of inter connected plates defining a stack. each plate having a first and second spaced-apart cutout to define an elongated exhaust passage communicating with the pipe line and a spaced-apart air flow duct, respectively, extending perpendicularly to said plates through said assembly, a plate member applied to an outermost plate of the stack facing in an upstream direction of the gas flow through the pipe line, the plate member and having an aperture positioned and shaped to correspond to the first cutout in the plates and a multiplicity of outlet ports evenly distributed along a full peripheral margin of the aperture in the plate member the outlet ports and being dimensioned to fluidly communicate the airflow duct with the exhaust passage, each port having a linear extent along the peripheral margin of the first cut out substantially less than the total length of the peripheral margin, a pair of end plates placed against and connected to the plate member and to another end of the stack, the end plates communicating the exhaust gas passage with the exterior of the stack and closing the airflow duct to prevent fluid communication between the duct and the exterior and to direct fluid flow in the duct through the ports and into the exhaust gas passage, and means defining a fluid flow conduit for connecting the airflow duct with a source of an oxidizing fluid, whereby the oxidizing fluid entering the duct will pass through the ports into the exhaust gas passage, will substantially homogeneously mix with the exhaust gas, and will oxidize the gases in the passage to reduce the pollutants therein. 

1. An exhaust emissions control device comprising: a platelet assembly including a multiplicity of stacked, interconnected plates, the plates having first aligned cutouts defining an elongated exhaust passage extending perpendicularly to said plates through said assembly, and aligned second cutouts spaced from the first cutouts and defining an elongate airflow duct extending generally perpendicularly to said plates through said assembly, a plate member connected to one end of said stacked plates, the plate member defining another first cutout aligned with the first cutout in said stacked plates and a multiplicity of spaced-apart outlet ports distributed along a peripheral margin of the first cutout in the plate member, the outlet ports being further positioned and dimensioned to overlie the second cutout defined by the plate in contact with the plate member to thereby place the airflow duct in fluid communication with the exhaust passage through the assembly, each port having a linear extent along the peripheral margin of the first cutout substantially less than the total length of the peripheral margin, a pair of end plates placed against and connected to the plate member and to another end of the stacked plates, the end plates including first cutouts aligned with the first cutouts in the assembly and the plate member to define a continuous exhaust gas passage through the assembly, the end plates further closing the airflow duct to prevent fluid communication between the duct and the exterior and to direct fluid flow in the duct through the ports and into the exhaust gas passage, and means defining a fluid flow conduit for connecting the airflow duct with a source of an oxidizing fluid, whereby the oxidizing fluid entering the duct will pass through the ports into the exhaust gas passage and will oxidize the gases in the passage to reduce the pollutants therein.
 2. An exhaust emission control device according to claim 1 wherein the ports are evenly distributed over the peripheral margin of the exhaust gas passage to effect a substantially homogeneous mixture of exhaust gas and oxidizing fluid in the exhaust gas passage.
 3. An exhaust emissions control device according to claim 1 including an exhaust gas flow conduit attached to the device, and wherein the device is mounted to the exhaust gas flow conduit so that the ports are positioNed at the upstream end of the exhaust gas flow through the device.
 4. An exhaust emissions control device according to claim 1 wherein each plate of the assembly, the plate member and the end plates define a plurality of spaced apart first cutouts to define a plurality of parallel exhaust gas passages through the device, the plates and the plate member further defining a plurality of second cutouts to define a duct on each side of each first cutout, and wherein the ports are defined by a multiplicity of spaced-apart teeth of said plate member extending partially across respective ducts so that the ports are defined by spaces between the teeth.
 5. An exhaust emissions control device according to claim 4 wherein the spacing between the teeth is non-uniform.
 6. An exhaust emissions control device according to claim 4 wherein the width of at least certain of said teeth is different from that of the other teeth to maintain the effective areas of corresponding ports substantially equal to each other.
 7. An exhaust emissions control device according to claim 1 wherein the depth of the duct in a direction parallel to the exhaust gas passage is substantially uniform.
 8. An exhaust emissions control device according to claim 1 wherein the depth of the duct in a direction parallel to the exhaust gas passage varies along said peripheral margin.
 9. An exhaust emissions control device installed in an exhaust gas pipe line having exhaust gas flowing therethrough, the device comprising: a multiplicity of interconnected plates defining a stack, each plate having a first and second spaced-apart cutout to define an elongated exhaust passage communicating with the pipe line and a spaced-apart air flow duct, respectively, extending perpendicularly to said plates through said assembly, a plate member applied to an outermost plate of the stack facing in an upstream direction of the gas flow through the pipe line, the plate member and having an aperture positioned and shaped to correspond to the first cutout in the plates and a multiplicity of outlet ports evenly distributed along a full peripheral margin of the aperture in the plate member the outlet ports and being dimensioned to fluidly communicate the airflow duct with the exhaust passage, each port having a linear extent along the peripheral margin of the first cut out substantially less than the total length of the peripheral margin, a pair of end plates placed against and connected to the plate member and to another end of the stack, the end plates communicating the exhaust gas passage with the exterior of the stack and closing the airflow duct to prevent fluid communication between the duct and the exterior and to direct fluid flow in the duct through the ports and into the exhaust gas passage, and means defining a fluid flow conduit for connecting the airflow duct with a source of an oxidizing fluid, whereby the oxidizing fluid entering the duct will pass through the ports into the exhaust gas passage, will substantially homogeneously mix with the exhaust gas, and will oxidize the gases in the passage to reduce the pollutants therein. 